tcp/dccp: complete lockless accesses to sk->sk_max_ack_backlog

[ Upstream commit 9a79c65 ]

Since commit 099ecf5 ("net: annotate lockless accesses to
sk->sk_max_ack_backlog") decided to handle the sk_max_ack_backlog
locklessly, there is one more function mostly called in TCP/DCCP
cases. So this patch completes it:)

Signed-off-by: Jason Xing <[email protected]>
Reviewed-by: Eric Dumazet <[email protected]>
Link: https://lore.kernel.org/r/[email protected]
Signed-off-by: Jakub Kicinski <[email protected]>
Stable-dep-of: 3479c75 ("tcp/dccp: allow a connection when sk_max_ack_backlog is zero")
Signed-off-by: Sasha Levin <[email protected]>

Author: JasonXing

include/net/inet_connection_sock.h

@@ -282,7 +282,7 @@ static inline int inet_csk_reqsk_queue_len(const struct sock *sk)
 
 static inline int inet_csk_reqsk_queue_is_full(const struct sock *sk)
 {
-	return inet_csk_reqsk_queue_len(sk) >= sk->sk_max_ack_backlog;
+	return inet_csk_reqsk_queue_len(sk) >= READ_ONCE(sk->sk_max_ack_backlog);
 }
 
 bool inet_csk_reqsk_queue_drop(struct sock *sk, struct request_sock *req);